This circuit was obtained from 1967 documentation. It uses a sensor to determine the trigger point. The components are of the time, difficulty to obtain these days.
This circuit was found in the January 1989 issue of Radio Electronics magazine. The circuit sends...
We found this TTL power supply circuit in the December 1972 issue of Radio Electronics magazine. The...
This circuit was found in an American documentation from the 1980s. The sensitivity ranges from...